The present invention is an improvement over the fabric picking device described in U.S. Pat. No. 3,940,125 (Morton). More specifically, the device herein described is a fabric picking mechanism with self-adjusting features which eliminate certain problems found in operating the prior device. Except for these new features, their design and operation, the apparatus of the aforesaid U.S. Pat. No. 3,940,125 is hereby incorporated by reference herein.
The fabric picker shown and described in the prior device has the capability of picking a single fabric ply from a stack of material. This equipment has been used commercially for many years but certain inherent problems have resulted which the present invention has solved.
The accuracy of picking single ply material from a stack thereof depends primarily upon the following factors:
a) the pressure transmitted by the picker wheel on the top ply to be picked, which determines proper engagement between the picker wheel and the ply;
b) the clearance between the picker wheel and the shoe to accommodate different thicknesses of fabric; and
c) finally the frictional engagement between the bottom of the shoe and the top ply to prevent slippage of the fabric under the shoe when the top ply is engaged by the picker wheel.
In the prior picking device of U.S. Pat. No. 3,940,125 the clearance between the picker wheel and the shoe had to be adjusted manually for different thicknesses of fabric. Setting the clearance using a micrometer screw and feeler gauges is tedious and requires considerable experience. If the clearance is not very close to a recommended figure, the picker will mispick or double pick.
In the prior picking device, the force applied by the picker shoe on the top fabric ply to prevent slippage of fabric under the shoe is generated by a small torsion spring and cannot be significantly altered. Depending upon the slipperiness and stiffness of fabric being picked this spring force may be insufficient to keep intact the top ply and next ply of the stack so that rotation of the picking wheel actually pushes the top ply under the shoe rather than between the wheel and the shoe.
It is the purpose of the present invention to solve these problems which are inherent in the prior picking device.